#include "threadpool.h"
#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

const int NUMBER = 2;
// 任务结构体
typedef struct Task
{
    void (*function)(void *arg);
    void *arg;
} Task;

// 线程池结构体
struct ThreadPool
{
    // 任务队列
    Task *taskQ;
    int queueCapacity;         // 容量
    int queueSize;             // 当前任务个数
    int queueFront;            // 队头
    int queueRear;             // 队尾
    pthread_t managerID;       // 管理者线程ID
    pthread_t *threadIDs;      // 工作的线程ID
    int minNum;                // 最小线程数量
    int maxNum;                // 最大线程数量
    int busyNum;               // 忙的线程的个数
    int liveNum;               // 存活的线程的个数
    int exitNum;               // 要销毁的线程个数
    pthread_mutex_t mutexPool; // 锁整个线程池
    pthread_mutex_t mutexBusy; // 锁busyNum

    pthread_cond_t notFull;  // 判断队列满
    pthread_cond_t notEmpty; // 判断队列空
    int shutdown;            // 是不是销毁线程池，销毁为1
};

ThreadPool *threadPoolCreate(int min, int max, int queueSize)
{
    ThreadPool *pool = (ThreadPool *)malloc(sizeof(ThreadPool));
    do
    {
        if (pool == NULL)
        {
            printf("malloc threadpool fail \n");
            break;
        }
        pool->threadIDs = (pthread_t *)malloc(sizeof(pthread_t) * max);
        if (pool->threadIDs == NULL)
        {
            printf("malloc threadIDs fail \n");
            break;
        }
        memset(pool->threadIDs, 0, sizeof(pthread_t) * max);
        pool->minNum = min;
        pool->maxNum = max;
        pool->busyNum = 0;
        pool->liveNum = min;
        pool->exitNum = 0;
        if (pthread_mutex_init(&pool->mutexPool, NULL) != 0 ||
            pthread_mutex_init(&pool->mutexBusy, NULL) != 0 ||
            pthread_cond_init(&pool->notEmpty, NULL) != 0 ||
            pthread_cond_init(&pool->notFull, NULL) != 0)
        {
            printf("mutex or condition init fail \n");
            break;
        }
        pool->taskQ = (Task *)malloc(sizeof(Task) * queueSize);
        pool->queueCapacity = queueSize;
        pool->queueSize = 0;
        pool->queueFront = 0;
        pool->queueRear = 0;
        pool->shutdown = 0;
        // 管理线程和工作线程创建
        pthread_create(&pool->managerID, NULL, manager, pool);
        for (int i = 0; i < min; i++)
        {
            pthread_create(&pool->threadIDs[i], NULL, worker, pool);
        }
        return pool;
    } while (0);
    // 释放资源
    if (pool && pool->threadIDs)
    {
        free(pool->threadIDs);
    }
    if (pool && pool->managerID)
    {
        free(pool->managerID);
    }
    if (pool)
    {
        free(pool);
    }
    return NULL;
}

void *worker(void *arg)
{
    ThreadPool *pool = (ThreadPool *)arg;
    while (1)
    {
        pthread_mutex_lock(&pool->mutexPool);
        // 当前队列是否为空
        while (pool->queueSize == 0 && !pool->shutdown)
        {
            // 阻塞工作线程
            pthread_cond_wait(&pool->notEmpty, &pool->mutexPool);
            // 判断是否销毁线程
            if (pool->exitNum > 0)
            {
                pool->exitNum--;
                if (pool->liveNum > pool->minNum)
                {
                    pool->liveNum--;
                    pthread_mutex_unlock(&pool->mutexPool);
                    threadExit(pool);
                }
            }
        }
        // 判断线程池是否关闭
        if (pool->shutdown)
        {
            pthread_mutex_unlock(&pool->mutexPool);
            threadExit(pool);
        }
        // 从任务队列取任务
        Task task;
        task.function = pool->taskQ[pool->queueFront].function;
        task.arg = pool->taskQ[pool->queueFront].arg;
        // 移动头节点
        pool->queueFront = (pool->queueFront + 1) % pool->queueCapacity;
        pool->queueSize--;
        // 解锁
        pthread_cond_signal(&pool->notFull);
        pthread_mutex_unlock(&pool->mutexPool);
        // 工作
        pthread_t pid = pthread_self();
        printf("thread %ld start working \n", pid);
        pthread_mutex_lock(&pool->mutexBusy);
        pool->busyNum++;
        pthread_mutex_unlock(&pool->mutexBusy);

        task.function(task.arg);
        free(task.arg);
        task.arg = NULL;
        printf("thread %ld end working \n", pid);

        pthread_mutex_lock(&pool->mutexBusy);
        pool->busyNum--;
        pthread_mutex_unlock(&pool->mutexBusy);
    }
}

void *manager(void *arg)
{
    ThreadPool *pool = (ThreadPool *)arg;
    while (!pool->shutdown)
    {
        // 每隔3秒访问一次
        sleep(3);
        // 取出线程池中任务的数量和当前线程的数量
        pthread_mutex_lock(&pool->mutexPool);
        int queueSize = pool->queueSize;
        pthread_mutex_unlock(&pool->mutexPool);
        int liveNum = threadPoolAliveNum(pool);
        // 取出线程池中工作线程的数量
        int busyNum = threadPoolBusyNum(pool);
        // 添加线程
        // 任务个数>存活线程个数 && 存活线程数 < 最大线程数
        if (queueSize > liveNum && liveNum < pool->maxNum)
        {
            pthread_mutex_lock(&pool->mutexPool);
            int counter = 0;
            for (int i = 0; i < pool->maxNum && counter < NUMBER && pool->liveNum < pool->maxNum; i++)
            {
                if (pool->threadIDs[i] == 0)
                {
                    pthread_create(&pool->threadIDs[i], NULL, worker, pool);
                    counter++;
                    pool->liveNum++;
                }
            }
            pthread_mutex_unlock(&pool->mutexPool);
        }
        // 销毁线程
        // 忙线程*2 < 存活线程数 && 存活的线程 > 最小线程数
        if (busyNum * 2 < liveNum && liveNum > pool->minNum)
        {
            pthread_mutex_lock(&pool->mutexPool);
            pool->exitNum = NUMBER;
            pthread_mutex_unlock(&pool->mutexPool);
            // 工作线程自杀
            for (int i = 0; i < NUMBER; i++)
            {
                pthread_cond_signal(&pool->notEmpty);
            }
        }
    }
}

void threadExit(ThreadPool *pool)
{
    pthread_t tid = pthread_self();
    for (int i = 0; i < pool->maxNum; i++)
    {
        if (pool->threadIDs[i] == tid)
        {
            pool->threadIDs[i] = 0;
            printf("threadExit called, %ld exiting \n", tid);
            break;
        }
    }
    pthread_exit(NULL);
}

void threadPoolAdd(ThreadPool *pool, void (*func)(void *), void *arg)
{
    pthread_mutex_lock(&pool->mutexPool);
    while (pool->queueSize == pool->queueCapacity && !pool->shutdown)
    {
        // 阻塞生产者线程
        pthread_cond_wait(&pool->notFull, &pool->mutexPool);
    }
    if (pool->shutdown)
    {
        pthread_mutex_unlock(&pool->mutexPool);
        return;
    }
    // 添加任务
    pool->taskQ[pool->queueRear].function = func;
    pool->taskQ[pool->queueRear].arg = arg;
    pool->queueRear = (pool->queueRear + 1) % pool->queueCapacity;
    pool->queueSize++;
    pthread_cond_signal(&pool->notEmpty);
    pthread_mutex_unlock(&pool->mutexPool);
}

int threadPoolBusyNum(ThreadPool *pool)
{
    pthread_mutex_lock(&pool->mutexBusy);
    int busyNum = pool->busyNum;
    pthread_mutex_unlock(&pool->mutexBusy);
    return busyNum;
}

int threadPoolAliveNum(ThreadPool *pool)
{
    pthread_mutex_lock(&pool->mutexPool);
    int liveNum = pool->liveNum;
    pthread_mutex_unlock(&pool->mutexPool);
    return liveNum;
}

int threadPoolDestroy(ThreadPool *pool)
{
    if (pool == NULL)
    {
        return -1;
    }
    pool->shutdown = 1;
    // 阻塞回收管理者线程
    pthread_join(pool->managerID, NULL);
    // 唤醒阻塞的消费者线程
    for (int i = 0; i < pool->liveNum; i++)
    {
        pthread_cond_signal(&pool->notEmpty);
    }
    if (pool->taskQ)
    {
        free(pool->taskQ);
    }
    if (pool->threadIDs)
    {
        free(pool->threadIDs);
    }
    pthread_mutex_destroy(&pool->mutexPool);
    pthread_mutex_destroy(&pool->mutexBusy);
    pthread_cond_destroy(&pool->notEmpty);
    pthread_cond_destroy(&pool->notFull);
    free(pool);
    pool = NULL;
    return 0;
}
